1. Field of the Invention
The present invention relates to multi-range timer switch devices, and in particular to such a device for actuating a stationary switch means and having a scale division thereon corresponding to the speed of rotation of the timer switch device.
2. Description of the Prior Art
Timer switch discs are widely known and used for controlling a sequence of events wherein each event is initiated by the actuation of a switch by the timer device. Such timer devices have application in switching clocks, cycle control means, and time lag relays, as well as many other types of devices well known to those skilled in the art. For many such applications, it is particularly useful to select the time range for the timer device, which is governed by the speed of rotation of a programmable switching means, such as a disc, to be a standard daily, weekly, monthly or annual program.
Timer devices as described above are known in the art which utilize a synchronous motor and which provide daily and weekly program time ranges. In order to change from one program range to another, such devices include a mechanical gearing or drive train between the drive means and the switching disc by means of which the rotational speed of the switching disc can be changed, for example, from one revolution per 24 hours to one revolution per week, and vice versa. Such a switching device is described in German OS No. 2,835,518. This conventional timer has the disadvantage, however, that in addition to shifting the gears in order to change the period of revolution of the switching disc, it is also necessary to independently manually change the dial face for the disc in order to coordinate the time divisions on the dial face with the new rotational speed.
Because of the necessity of undertaking two separate and independent operations, namely shifting gears and changing dial faces, in conventional timer switching devices, errors may arise when only one of these operations is undertaken. Moreover, in such conventional devices it is difficult to precisely correlate the position of the divisions of the new dial face with the switching disc in order to accurately reflect elapsed time during the new rotational speed of the disc.
Another timer disc is described in German OS No. 3,002,570 which has a one-piece switching disc having a daily switching program on one side thereof and a weekly switching program on the other side so that the disc need only be turned over in order to alter or change the time range as well as the rotational speed of the disc. For engaging the appropriate drive train, the disc carries corresponding gear rims which are respectively engaged with a pinion of the appropriate drive train depending upon which side of the disc is facing up (that is, is visible). Thus the gear rim for the daily time range is disposed on the face of the disc having a scale division for the weekly time range, and the gear rim for the weekly time range is disposed on the face of the disc with the scale division for the daily time range. This known device still, however, presents problems in accurately setting the particular dial face in use to the time of day at which the change-over from one rotational speed to the other is made, due to the pitch of the teeth in the respective gear rims relative to the central pinion of the drive train which engages the gear rims. Moreover, the position of the switching disc must still be adjusted relative to the switch actuators.